Multi mode wireless devices that are compatible with more than one form of data transmission or network are known. Such devices include for example mobile devices such as mobile phones, personal digital assistants, etc., and M2M (machine-to-machine) gateway devices. A particular type of multi mode wireless device, often termed a dual mode device, contains both cellular and non-cellular radios which are used for voice and data communication respectively. Examples of cellular technologies include GSM (Global System for Mobile Communications), CDMA (Code Division Multiple Access), W-CDMA (Wideband Code Division Multiple Access) and LTE (Long Term Evolution), though many others are known. Examples of non-cellular technologies include WLAN IEEE802.11 and BLUETOOTH® wireless technology, though again many others are known.
In typical prior art approaches, the hardware for the cellular aspect of the dual band wireless device is provided in addition to and, in essence, separately of the hardware for the non-cellular aspect of the dual band wireless device. This is shown schematically in FIG. 1 which shows schematically some of the internal components of a prior art dual band wireless device 10. There are entirely separate hardware components for each of the cellular and non-cellular radios, including in particular the radio frequency parts 20,30, the processor(s) 21,31 for the layer 1 processing, and the processor(s) 22,32 for the layer 2 and above processing, for each of the cellular and non-cellular radios. It will be understood that the term “layer” here is used in the context of the Open Systems Interconnection (OSI) model, in which layer 1 is the physical layer, layer 2 is the data link layer, etc.
FIG. 2 shows the arrangement of processors (which may each be individual chips or plural chips, optionally provided as a chipset) of one particular example of this prior art in more detail. On the cellular side (upper part of the diagram), there are separate processors 21,22 for the layer 1 processing and for the layer 2 and above processing respectively, each with their own software 23,24 and in communication with each other via an interconnect 25. Similarly, on the non-cellular side (lower part of diagram), there are separate processors 31,32 for the layer 1 processing and for the layer 2 and above processing respectively, each with their own software 33,34 and in communication with each other via an interconnect 35. In general, there is typically no communication between the cellular and non-cellular sides of the device 10.
This duplication of hardware inevitably raises costs and increases power consumption in use, and also increases the space required within the wireless device for the radio components. Power consumption is a particular concern when the cellular and non-cellular components are to be used simultaneously. This happens for example in the case of a mobile device used to transmit/receive both telephone calls and data simultaneously on cellular and non-cellular networks respectively, and in a M2M (machine-to-machine) gateway type device where data is simultaneously received and transmitted (typically on a non-cellular network and on a cellular network respectively, though other arrangements are possible).
A software-defined radio system (or SDR) is a radio communication system where components that have been typically been implemented in the past in hardware (such as mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software running on a personal computer or some embedded computing device such as a programmable processor. A SDR is inherently flexible in that in principle it can be reprogrammed to provide services according to different telecommunications standards. However, compared to a conventional non-SDR radio system having bespoke hardware, a SDR is relatively inefficient on power usage and often has poor dynamic range.
In US-B2-7817579, there is disclosed an access point for a network, which is used to allow mobile devices to connect wirelessly to the network. The access point has plural software defined radios (SDRs), including in particular SDR programmable logic blocks which configure plural physical layer (layer 1) blocks. The corresponding MAC (layer 2) blocks may be implemented in part or fully by a single processor. Nevertheless, there is shown only a single radio front end, indicating that only one of the SDRs can be active at any particular time, and also no discussion of integration of hardware that concerns higher layers above level 2.
US-A1-2010/0144333 discloses a SDR that includes a programmable cellular radio front end and a programmable baseband processor. The cellular radio front end can be reconfigured so as to support a non-cellular transmission standard. Again, there is only a single radio front end and the SDR cannot be communicating with a cellular network and a non-cellular network simultaneously.